Definition: A carboxylic acid is a type of organic acid that has one or more carboxyl groups. A carboxyl group is a part of a molecule that contains both a carbon atom and two oxygen atoms (one of which is bonded to a hydrogen atom). This structure gives carboxylic acids their acidic properties.
"Carboxylic acid" specifically refers to the chemical category of compounds, so it does not have multiple meanings like some other words in English.
There are no idioms or phrasal verbs specifically related to "carboxylic acid," as it is a technical term in chemistry.
In summary, "carboxylic acid" is a scientific term for a specific type of acid with a carboxyl group.